The invention relates to a medical instrument for treating, in particular for removing tissue, bone cement or the like in the human or animal body, comprising a hand piece and an application part arranged on the distal end of same, wherein the application part is axially movable to-and-fro relative to the hand piece, wherein the hand piece contains a drive mechanism for the application part, which transfers a pressure being continuously present in the hand piece in the to-and-fro movement of the application part.
Such an instrument is known from DE 34 39 434 A1.
The known instrument mentioned before serves for the creation of mechanical oscillations for medical curing purposes even in deeper body layers.
An instrument mentioned at the outset is to be suitable, according to the present invention to remove biological tissue, in particular soft or fatty tissue, from the human or animal body. A special application of such an instrument is the removal by suction of fat within the scope of cosmetic surgery. Another application of such an instrument is the removal of bone cement, by which an endoprosthesis, e.g. a hip joint endoprosthesis, is anchored in a bone of the human skeleton, in order to be able to take the endoprosthesis out of the bone for the purpose of revision.
From U.S. Pat. No. 5,685,840, an instrument is known that has an application part having an opening at its distal end and a cutting element moving to-and-fro within the stationary application part, which cuts off tissue sucked into the opening of the application part in co-action with the edge of the opening. As a drive for the cutting element moving to-and-fro in the application part, an electric motor is provided, which is arranged in the hand piece.
A disadvantage of this instrument is that the removed tissue, first of all, is sucked into the opening and, subsequently, is cut off, so that it cannot be prevented that also vessels are sucked into the opening and cut, which may result in considerable bleedings.
A further disadvantage of such an instrument is that the instrument itself has a high weight due to the motor integrated in the hand piece, which results in a quick fatigue of the user""s hand. Furthermore, a movement transforming element is necessary in order to transform the rotation movement of the motor into an axial movement of the cutting element. This movement transforming element is also relatively large and heavy, and losses occur in the transformation from the rotation movement into the axial movement of the cutting element.
For the disintegration of soft tissue, purely mechanical instruments are also known, which are configured in the shape of cannulas, these being connected to a common syringe. By moving to-and-fro the cannula by hand, fatty tissue can be separated and sucked off by means of the syringe.
The disadvantage of these instruments is that by the mechanical movement transmitted by hand and the large lengths of stroke resulting therefrom of the to-and-fro movement, not only fatty tissue, but also blood vessels and other tissue may be removed, which may result in inner injuries and inflammations.
Further, from U.S. Pat. No. 4,886,491, a method for tissue removal with an ultrasound instrument is known, in which an ultrasound suction cannula is entered into the body in the area of the soft tissue or the fatty tissue. The cannula is excited to high frequency oscillations with low amplitude by means of ultrasound, whereby a local mechanical tissue disintegration, but also additional frictional heat is generated. The disintegrated fatty tissue is then sucked off via the cannula.
The disadvantage of ultrasound supported tissue removal is that operations of longer duration, as it is the case particularly in the abdominal area, which may last up to four hours, cause a significant heating of the ultrasound hand piece, which cannot be prevented even by additional irrigation. Moreover, the ultrasound hand pieces with the piezo-oscillators are relatively large and heavy. This is a problem in particular for fat removal in the face area. Apart from that, the piezo-elements are to be run with relatively high voltages, which causes additional insulation problems and safety problems. Also, the tissue removal speed or the disintegration speed is not satisfying.
On the other hand, it could be envisaged to use the instrument of WO 99/09897 used in pneumatic lithotripsy, which is used for fragmentation of hard concrements, like e.g. body stones, in modified form also for removal of tissue, in particular soft tissue and fatty tissue. In this known instrument for pneumatic lithotripsy, a bolt movable in a probe is axially moved to-and-fro by means of compressed-air impulses, wherein the probe impulse transmitted by the bolt fragmentizes the concrement to be dissolved.
Another lithotripter of that kind is known from DE 44 05 656 A1, in which the probe transmitting the shock waves runs in a stationary guide tube, which has a take-in and/or suction conduit for the stones that were smashed by the probe.
The disadvantage of such pneumatic lithotripsy instruments is the low repeat frequency of the movement of the probe, which is less than 20 Hz, and the relatively large hand piece. The low repeat frequency of the probe movement is due to the fact that pressure impulses have to be generated, and that the bolt has to be moved back into its initial position after each shot. Apart from that, besides the hand piece and a compressed-air supply, an additional device for the generation of pressure impulses is necessary. Such a pneumatic lithotripsy instrument, which is optimized for the fragmentation of concrements due to the very high probe speed and the very strong probe impulse, is extremely expensive for the removal of tissue or bone cement.
The instrument known from DE 34 39 434 A1 mentioned at the outset has as application part a probe, a cannula or a needle, in the distal part of which there is a linear motor having a piston, which is moved to-and-fro by a pressure of a fluid, in order to generate oscillations up to approximately 20 kHz, to reach different biological effects in different parts of the body, even deep in the inner part of the body. This known instrument is not adapted for the removal of soft tissue and fatty tissue due to the configuration of the application part, which is formed by the piston itself.
The invention has, thus, the object to provide an instrument of the type mentioned at the outset, by which tissue, in particular soft tissue and fatty tissue, can be removed without the danger of bleedings and inner injuries, as well as bone cement and the like.
This object is achieved by a medical instrument for treating, in particular a medical instrument for treating, in particular for removing tissue, bone cement or the like in the human or animal body, comprising:
a hand piece having a distal end;
an application part arranged at said distal end of said hand piece, said application part being axially movable to-and-fro relative to said hand piece, said application part having at least in a region of a distal end of said application part a conduit, which has, in a distal region of said conduit, at least a suction and/or irrigation aperture; and
a drive mechanism for said application part, said drive mechanism being provided in said hand piece, said drive mechanism transferring a pressure being continuously present in said hand piece into said to-and-fro movement of said application part.
In the instrument according to the invention, the application part itself is, thus, axially movable to-and-fro relative to the hand piece, whereby the tissue to be removed is gently loosened by the application part. In particular fat particles may be released from the tissue compound and sucked off through the configuration according to the invention as hollow probe, and/or an irrigation liquid may be fed into the area to be treated in order to facilitate sucking off tissue or bone cement.
In comparison to the known instruments in which the tissue to be cut off is sucked through an opening into the application part and is cut off by a cutting element, the danger of cutting off or cutting blood vessels and, thus, of bleedings is avoided.
Just the combination of the application part being moved to-and-fro by the existing pressure and its simultaneous configuration as a hollow probe result in a construction that is simple in design and in a particular suitability of the instrument for the removal of soft tissue and fatty tissue.
While the known shaver instruments solely cut actively the tissue to be removed, the instrument of the invention allows tissue compounds to be mechanically dissolved and/or to be disintegrated. By making use of a continuously present pressure as drive mechanism for the application part, the pressure being transformed into a to-and-fro movement of the application part, in comparison to the instruments known from the pneumatic lithotripsy, the advantage is created that the repeat frequency of the to-and-fro movement can be increased considerably. Repeat frequencies of more than 50 Hz can be reached. In comparison to purely mechanical instruments, which are moved to-and-fro by hand, and for which the stroke of movement is large and not exactly controllable, the stroke of movement of the application part can be, due to the drive mechanism, limited to approximately 0.1 mm to 5 mm or to 10 mm, depending on the application. The instrument of the invention is not only suited for the removal of tissue or bone cement, but can also be used advantageously for stimulation of tissue areas by transmission of kinetic energy into the tissue area to be treated for the therapy of inflammations or articulation diseases, nervous inflammations or for the stimulation of the blood circulation.
Due to the simple and cost-effective construction, the instrument can also be manufactured as one-way instrument, so that cleaning and sterilization can be omitted.
In a preferred embodiment, the pressure is created by compressed air and the drive mechanism is configured in the manner of a pneumatic-mechanical oscillating circuit, which has as active elements the pneumatic pressure and at least one energy storage element, preferably a spring.
By this configuration, a cost-effective drive mechanism that is simple in construction for the application part is created, which combines the continuously present pressure with an energy storing element, in particular a spring, to a pneumatic-mechanical oscillating circuit.
In another preferred embodiment, the compressed air is generated in an external compressed-air source and is supplied to the hand piece via a line.
In this method, it is advantageous that the hand piece itself can be configured in a slender fashion and low in weight because the compressed-air source needs not to be located in the hand piece. A compressed-air bottle, a local or a central compressor system (hospital internal compressed-air supply) may be used as compressed-air source.
In a further preferred embodiment, the drive mechanism has a pressure chamber arranged in the hand piece, which has at least a proximal air inlet opening and, arranged on the distal side thereof, at least a lateral air outlet opening is arranged, and in the pressure chamber there is a piston connected to the application part, which is biased by the energy storing element in the direction against the pressure.
By this measure, a pneumatic-mechanical oscillating circuit is created that is particularly simple in design and easy to be maintained, wherein the oscillation of the drive mechanism and, thus, the to-and-fro movement of the application part is caused by the combination of the piston with the at least one lateral air outlet opening. The continuously present pressure moves the piston into the distal direction, thus tensing the spring, wherein the piston in its movement into the distal direction clears the at least one air outlet opening, out of which the compressed air can escape, whereby the pressure in the pressure chamber is reduced and the spring moves back the piston after the air outlet, after which the pressure in the pressure chamber is increased again, so that, altogether, a periodic movement of the application part is caused.
In another preferred embodiment, the pressure in the pressure chamber is adjustable via an adjustable pressure reducing valve.
It is advantageous herewith that the continuous pressure present in the pressure chamber can be adjusted in relation to the energy storing element and, thus, the movement speed of the application part and the length of stroke of the movement of the application part. Alternatively to a pressure reducing valve, the acting cross section of the air inlet opening, e.g. in form of an iris diaphragm, can also be variable in order to control the filling procedure of the pressure chamber.
In preferred embodiments, the pressure reducing valve in the hand piece is either arranged on the proximal side of the pressure chamber, or it is arranged in an external device between the compressed-air source and the hand piece.
Furthermore, it is also preferred if the pressure reducing valve is arranged directly on or in the compressed-air source.
In that way, the adjustment of the pressure present in the pressure chamber can be adjusted directly at the compressed-air source.
It is further preferred if the at least one suction and irrigation aperture is arranged laterally on the application part.
Due to the lateral arrangement of the opening, a danger of injury is avoided by the edges of the opening in the axial to-and-fro movement, while this is not guaranteed for an opening at the distal end of the application part.
In another preferred embodiment, a distal point of the application part is closed and configured approximately in spherical cap shaped fashion.
While this configuration of the distal end is advantageously suited for the disintegration of soft tissue or fatty tissue, because a more gentle treatment of the tissue is guaranteed, it is also preferred according to another embodiment, if the application part has a distally open point, which forms the suction and irrigation aperture.
In this case, a gouge-like configuration is reached, by which bone cement in connection with the to-and-fro movement of the application part can be particularly efficiently removed. In this procedure, the edges of the distal open point can be additionally sharpened.
In further preferred embodiments, in the proximal region of the conduit, a connection piece for connecting a suction and/or irrigation line is arranged on the distal side of the hand piece, or the conduit extends until into the hand piece and opens into a connection piece at the proximal end of the hand piece for connecting a suction and/or irrigation line.
In the latter alternative, there is the advantage of a straight conduit for a better sucking off of removed tissue, and another advantage is a lesser disturbing influence of the user by any hoses in the region of the application part.
It is further preferred if the application part has at least one conduit for insufflation of a fluid into the treatment area.
In this embodiment, the disintegration of the tissue can be advantageously accelerated by insufflating a suitable fluid, whereby the duration of the treatment can be reduced in particular for fat removal operations.
It is further preferred if the at least one suction and/or irrigation aperture is configured as a blade on its edge.
By this measure, the tissue removal can be improved by the combination of mechanical disintegration and additional cutting effect of the edge of the irrigation opening when moving to-and-fro the application part, wherein, as distinguished from the known instruments, in which the tissue is solely sucked into the opening and cut off by means of a cutting element, in this method, a danger of blood vessel injuries is reduced.
In another preferred embodiment, the length of stroke and/or the frequency of the to-and-fro movement of the application part is adjustable.
It is advantageous herewith that the instrument according to the invention can be adapted to the respective application with respect to the stroke of movement or to the movement amplitude. The adaptability is preferably within a range of 0.1 mm to 5 mm or larger, e.g. 10 mm.
To this end, in another preferred embodiment, the effective cross section of the at least one air outlet opening can be reduced and enlarged.
By enlarging the air outlet opening, the pressure in the pressure chamber is reduced faster, when the piston clears the air outlet opening, whereby the movement amplitude of the piston is reduced, because the force stored in the energy storage, e.g. in the form of a spring, as counter force to the present pressure, exceeds the pressure already after shorter time and, thus, shorter movement way due to the faster pressure reduction and moves back the piston into the proximal direction. By reducing the air outlet opening, the stroke of movement of the piston is correspondingly enlarged until its return.
In particular, by an axial change of the effective cross section of the at least one air opening, essentially a change of the length of stroke of the application part can be reached, while a circumferential change of the effective cross section can result in a faster air outlet and, thus, in another frequency of the to-and-fro movement.
The stroke of movement and/or the frequency of the piston can, in that way, be adjusted by controlling the air outlet.
It is further preferred in this procedure, if around the pressure chamber an axially and/or circumferentially movable sleeve is arranged for continuous covering or exposing the at least one air outlet opening.
In this way, in a simple design and in an easy to handle manner, a regulating element for reducing and/or enlarging the air outlet opening and, thus, for reducing and/or enlarging the stroke of movement of the piston is created.
In order to effect also an additional electrically caused tissue disintegration, it is also preferred if the application part has at least one electrically insulated electrode, which is supplied with a high frequency voltage. In the case of only one electrode, the disintegration can be done in monopolar manner, in the case of two electrodes, the disintegration can be done in bipolar manner.
The tissue disintegration can also be advantageously improved, if additionally a generator element generating ultrasound can be coupled onto the application part.
In another preferred embodiment, the application part can be detached from the hand piece.
In that way, the instrument can easier and more thoroughly be cleaned due to the fact that it can be disassembled into hand piece and application part.
An even further improvement of the instrument according to the invention is reached in a preferred embodiment by arranging an endoscopic system in the application part, which transmits images and/or light, whereby the application of the instrument is endoscopically visualized in the treatment area and, thus, can be controlled.
Further advantages can be taken from the following description and the attached drawings.
It is to be understood that the features mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation, without leaving the scope of the present invention.